JP7147271B2 - Tire rubber composition and pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition for tires and a pneumatic tire produced using the same.

In the past, spiked tires and chains were attached to the tires for driving on snowy and icy roads, but because of environmental problems such as dust problems, studless tires have been proposed as an alternative. Studless tires are used on roads covered with snow and ice, which have more uneven road surfaces than ordinary roads, so they are devised in terms of materials and design. In order to enhance the softening effect, a rubber composition containing a large amount of a softening agent has been developed (see Patent Document 1, etc.).

Recently, in addition to the performance on ice and snow, from the viewpoint of the environment, it is required to impart good abrasion resistance at the same time, and it is desired to improve these performances in a well-balanced manner.

JP 2009-091482 A

The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a rubber composition for tires that improves performance on ice and snow and wear resistance in a well-balanced manner, and a tire using the same.

The present invention comprises a rubber component containing isoprene rubber and butadiene rubber, silica, a softening point of 60 to 150 ° C., an α-pinene unit content of 65 to 100% by mass, a β-pinene unit content of 0 to 35% by mass, and and a terpene-based resin having a limonene unit content of 10% by mass or less, the content of the isoprene-based rubber in 100% by mass of the rubber component is 5 to 80% by mass, and the content of the butadiene rubber is 5 to 80% by mass. %, the total content of the isoprene rubber and the butadiene rubber is 60% by mass or more, the content of the silica is 1 to 500 parts by mass with respect to 100 parts by mass of the rubber component, and the content of the terpene resin is 0 .1 to 100 parts by mass of the rubber composition for tires.

The terpene-based resin is an α-pinene homopolymer, a terpene-based resin having an α-pinene unit content of 99% by mass or more, and a copolymer having an α-pinene unit and a β-pinene unit. is preferably at least one.

The terpene resin preferably has a number average molecular weight of 500-775 and a z-average molecular weight of 1300-1600.
The silica content is preferably 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

The nitrogen adsorption specific surface area of silica is preferably 160 m ² /g or more.
The nitrogen adsorption specific surface area of silica is preferably 190 m ² /g or more.
The content of carbon black is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the rubber component.

The butadiene rubber preferably has a cis content of 90% by mass or more.
It is preferable to include 0.1 to 100 parts by mass of the polar plasticizer with respect to 100 parts by mass of the rubber component.
The glass transition temperature of the polar plasticizer is preferably −80° C. or lower.

The rubber composition has an E* at 0°C of 3.0 to 8.0, a difference between E* at -10°C and 10°C of 10.0 or less, and a tan δ at 0°C of 0.14 to 0.26. Preferably.

The present invention relates to a pneumatic tire having a tread made of the rubber composition.
The present invention also relates to a studless tire having a tread composed of the rubber composition.

The present invention is a tire rubber composition containing a rubber component containing an isoprene rubber and a butadiene rubber, silica, and a predetermined terpene resin in a predetermined blend, thereby improving performance on ice and snow and abrasion resistance in a well-balanced manner. can.

The rubber composition for tires includes a rubber component containing isoprene rubber and butadiene rubber, silica, a softening point of 60 to 150 ° C., an α-pinene unit content of 65 to 100% by mass, and a β-pinene unit content of 0 to 35% by mass and a terpene resin having a limonene unit content of 10% by mass or less are contained in a predetermined composition. Since a specific terpene-based resin is blended with a specific rubber component containing predetermined blends of isoprene-based rubber and butadiene rubber, performance on ice and snow and abrasion resistance are improved in a well-balanced manner.

Although the reason why such an effect is obtained is not clear, it is presumed to be due to the following functions.
The specific terpene-based resins, particularly those in which the α-pinene-derived component is within the scope of the present invention, are particularly excellent in compatibility with isoprene-based rubbers, so that they can be used, for example, in soft rubber compositions such as winter tires. It is presumed that the performance on ice and snow can be improved without lowering the wear resistance even if it is blended in. In addition, by controlling the softening point and molecular weight (Mn, Mz, Mw, etc.) of the terpene-based resin within the above-described predetermined range, the compatibility with isoprene-based rubber is further improved, and deterioration of performance due to bloom etc. can be prevented. Therefore, it is presumed that the performance on ice and snow will be maintained for a long period of time. Therefore, the rubber composition can remarkably improve the performance balance between performance on ice and snow and wear resistance, and can also provide good long-term maintenance performance (durability) of these performances.

Furthermore, the rubber composition can impart good fuel efficiency and steering stability, and the performance balance among ice and snow performance, wear resistance, fuel efficiency and steering stability is remarkably improved.

(rubber component)
The rubber composition includes a rubber component containing an isoprene rubber and a butadiene rubber.
The isoprene rubber includes natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. NR may be SIR20, RSS#3, TSR20, etc., and IR may be IR2200, etc., which are commonly used in the tire industry. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., modified IR Examples include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more.

The content of isoprene-based rubber in 100% by mass of the rubber component is 5% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, from the viewpoint of performance balance between performance on ice and snow and abrasion resistance. More preferably, it is 40% by mass or more. The content is 80% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less.

The butadiene rubber (BR) is not particularly limited, and examples thereof include BR with a high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), and butadiene synthesized using a rare earth catalyst. Rubber (rare earth-based BR), tin-modified butadiene rubber modified with a tin compound (tin-modified BR), and other rubbers commonly used in the tire industry can be used. Commercially available BR products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used. These may be used alone or in combination of two or more.

The cis content of BR is preferably 90% by mass or more, more preferably 95% by mass or more, from the viewpoint of good performance on ice and snow, abrasion resistance, and the like.
In this specification, the cis content (cis-1,4-bond amount) is a value calculated from signal intensity measured by infrared absorption spectroscopy or NMR analysis.

The content of BR in 100% by mass of the rubber component is 5% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably, from the viewpoint of performance balance between performance on ice and snow and abrasion resistance. is 40% by mass or more. Moreover, the upper limit of the content is 80% by mass or less, preferably 70% by mass or less, and more preferably 60% by mass or less.

Both non-denatured BR and denatured BR can be used as BR.
As the modified BR, a BR having a functional group that interacts with a filler such as silica can be used. For example, at least one end of BR is modified with a compound (modifier) having the above functional group (end-modified BR having the above functional group at the end), or a main chain having the above functional group Chain modified BR, main chain terminal modified BR having the above functional group on the main chain and terminal (for example, main chain terminal modified BR having the above functional group on the main chain and at least one terminal modified with the above modifying agent ), modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule to introduce a hydroxyl group or an epoxy group, and the like.

Examples of the functional groups include amino group, amido group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group and the like. . In addition, these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( An alkoxysilyl group having 1 to 6 carbon atoms is preferred.

As the modified BR, for example, (1) BR modified with a compound (modifying agent) represented by the following formula can be preferably used.

In the above formula, R ¹ , R ² and R ³ are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (--COOH), a mercapto group (--SH) or a derivative thereof. . R ⁴ and R ⁵ are the same or different and represent a hydrogen atom or an alkyl group. ^R4 and ^R5 may combine to form a ring structure with the nitrogen atom. n represents an integer.

Modified BR modified with a compound (modifying agent) represented by the above formula includes, among others, BR modified with a compound represented by the above formula at the polymerization terminal (active terminal) of butadiene rubber in solution polymerization. It is preferably used.

R ¹ , R ² and R ³ are preferably alkoxy groups (preferably C 1-8 alkoxy groups, more preferably C 1-4 alkoxy groups). An alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable for R ⁴ and R ⁵ . n is preferably 1-5, more preferably 2-4, even more preferably 3. Also, when R ⁴ and R ⁵ combine to form a ring structure with a nitrogen atom, it is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

Specific examples of the modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane and the like. Among them, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferred. These may be used alone or in combination of two or more.

As the modified BR, modified BR modified with the following compounds (modifying agents) can also be suitably used. Modifiers include, for example, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having a phenol group of; 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxy compounds such as polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenyl epoxy group-containing tertiary amines such as methylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidylorthotoluidine, tetraglycidylmetaxylenediamine , tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane and other diglycidylamino compounds;

amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride and N,N-diethylcarbamic acid chloride;1 , 3-bis-(glycidyloxypropyl)-tetramethyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane and other epoxy group-containing silane compounds;

(trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl]sulfide, (trimethylsilyl)[3 -(tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(methyldimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(methyldiethoxysilyl) propyl] sulfide, (trimethylsilyl) [3-(methyldi sulfide group-containing silane compounds such as propoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane; 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N, N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, N,N,N',N' -(thio)benzophenone compounds having amino groups and/or substituted amino groups such as bis-(tetraethylamino)benzophenone; 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N, Benzaldehyde compounds having amino groups and/or substituted amino groups such as N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl- 2-pyrrolidone, N-substituted pyrrolidones such as N-methyl-5-methyl-2-pyrrolidone, N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone ; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-lauryrolactam, N-vinyl-ω-lauryrolactam, N-methyl-β-propiolactam, N-phenyl - N-substituted lactams such as β-propiolactam;

N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5 -triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3 -diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenyl amino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone and the like. Of these, modified BR modified with alkoxysilane is preferred.
Modification with the above compound (modifying agent) can be carried out by a known method.

Another example of the modified BR is (2) a modification reaction in which a BR having an active terminal is used and an alkoxysilane compound having two or more reactive groups containing an alkoxysilyl group is introduced into the active terminal of the BR. the modification step (A) to be carried out and the presence of a condensation catalyst containing at least one element selected from the group consisting of elements contained in groups 4, 12, 13, 14 and 15 of the periodic table and a condensation step (B) in which the residue of the alkoxysilane compound introduced to the active terminal is subjected to a condensation reaction, and the BR is a catalyst mainly composed of a mixture of the following components (a) to (c): Also included are those obtained by a manufacturing method using BR polymerized in the presence of the composition.
Component (a): A lanthanoid-containing compound containing at least one element selected from the group consisting of lanthanides, or a reaction product obtained by reacting the lanthanoid-containing compound with a Lewis base Component (b): Alumino and an organoaluminum compound represented by general formula (1): AlR ^a R ^b R ^c (wherein R ^a and R ^b are the same or different and have represents a hydrocarbon group or a hydrogen atom of R ^c is the same or different from R ^a and R ^b and represents a hydrocarbon group having 1 to 10 carbon atoms.) At least one compound selected from the group consisting of Component (c): an iodine-containing compound containing at least one iodine atom in its molecular structure

That is, a modification reaction is performed to introduce an alkoxysilane compound to the active terminal of BR (BR (I)) having an active terminal, and the modified BR (modified BR (I )) can be manufactured.

The modification step (A) uses BR (BR(I)) having an active terminal, and a modification reaction of introducing an alkoxysilane compound having two or more reactive groups containing an alkoxysilyl group to the active terminal of this BR. It is a process of performing

BR(I) is selected from the group consisting of, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and myrcene Polymers having repeat units derived from at least one monomer can be used.

When producing BR(I), the polymerization may be carried out using a solvent or may be carried out in the absence of a solvent. As the solvent used for polymerization (polymerization solvent), an inert organic solvent can be used. Saturated alicyclic hydrocarbons with 6 to 20 carbon atoms such as pentane and cyclohexane, monoolefins such as 1-butene and 2-butene, aromatic hydrocarbons such as benzene, toluene and xylene, methylene chloride, chloroform, tetrachloride Halogenated hydrocarbons such as carbon, trichlorethylene, perchlorethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene, chlorotoluene, and the like can be mentioned.

The polymerization reaction temperature for producing BR(I) is preferably -30 to 200°C, more preferably 0 to 150°C. The form of the polymerization reaction is not particularly limited, and may be carried out using a batch type reactor, or may be carried out continuously using an apparatus such as a multi-stage continuous reactor. When a polymerization solvent is used, the monomer concentration in this solvent is preferably 5 to 50% by mass, more preferably 7 to 35% by mass. In addition, from the viewpoint of the efficiency of BR production and from the viewpoint of not deactivating BR having an active terminal, the polymerization system should not be mixed with deactivating compounds such as oxygen, water, or carbon dioxide as much as possible. is preferred.

Here, as the BR (I), a BR polymerized in the presence of a catalyst composition (hereinafter also referred to as a "catalyst") containing a mixture of the components (a) to (c) as a main component is used. .

The above component (a) is a lanthanoid-containing compound containing at least one element selected from the group consisting of lanthanides, or a reaction product obtained by reacting the lanthanoid-containing compound with a Lewis base. Among the lanthanoids, neodymium, praseodymium, cerium, lanthanum, gadolinium, and samarium are preferred, and neodymium is particularly preferred. The lanthanoids may be used singly or in combination of two or more. Specific examples of the lanthanoid-containing compounds include lanthanoid carboxylates, alkoxides, β-diketone complexes, phosphates, and phosphites. Among these, carboxylates or phosphates are preferred, and carboxylates are more preferred.

Specific examples of the lanthanide carboxylates include salts of carboxylic acids represented by the general formula (2); (R ^d —COO) ₃ M (provided that M represents a lanthanide, and R ^d is the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms.). In general formula (2) above, R ^d is preferably a saturated or unsaturated alkyl group, preferably a linear, branched or cyclic alkyl group. Carboxyl groups are also attached to primary, secondary or tertiary carbon atoms. Specifically, octanoic acid, 2-ethylhexanoic acid, oleic acid, stearic acid, benzoic acid, naphthenic acid, trade name "Versatic acid" (manufactured by Shell Chemical Co., Ltd., the carboxyl group is bonded to the tertiary carbon atom carboxylic acid) and the like. Among these, salts of versatic acid, 2-ethylhexanoic acid and naphthenic acid are preferred.

Specific examples of the lanthanoid alkoxides include general formula (3); (R ^e O) ₃ M (where M represents a lanthanoid in general formula (3)). ). In the general formula (3), specific examples of the alkoxy group represented by "R ^e O" include a 2-ethyl-hexylalkoxy group, an oleylalkoxy group, a stearylalkoxy group, a phenoxy group, a benzylalkoxy group, and the like. is mentioned. Among these, a 2-ethyl-hexylalkoxy group and a benzylalkoxy group are preferred.

Specific examples of the β-diketone complexes of the lanthanoids include acetylacetone complexes, benzoylacetone complexes, propionitrileacetone complexes, valerylacetone complexes, ethylacetylacetone complexes, and the like. Among these, an acetylacetone complex and an ethylacetylacetone complex are preferred.

Specific examples of the lanthanoid phosphates or phosphites include bis(2-ethylhexyl) phosphate, bis(1-methylheptyl) phosphate, bis(p-nonylphenyl) phosphate, bis(p-nonylphenyl) phosphate, polyethylene glycol-p-nonylphenyl), (1-methylheptyl) phosphate (2-ethylhexyl), (2-ethylhexyl) phosphate (p-nonylphenyl), 2-ethylhexylphosphonate mono-2-ethylhexyl, 2- mono-p-nonylphenyl ethylhexylphosphonate, bis(2-ethylhexyl)phosphinic acid, bis(1-methylheptyl)phosphinic acid, bis(p-nonylphenyl)phosphinic acid, (1-methylheptyl)(2-ethylhexyl) Salts of phosphinic acid, (2-ethylhexyl)(p-nonylphenyl)phosphinic acid and the like are included. Among these, bis(2-ethylhexyl) phosphate, bis(1-methylheptyl) phosphate, mono-2-ethylhexyl 2-ethylhexylphosphonate, and bis(2-ethylhexyl)phosphinic acid salts are preferred.

Among these, the lanthanoid-containing compound is particularly preferably neodymium phosphate or neodymium carboxylate, and most preferably neodymium versatate or neodymium 2-ethylhexanoate.

In order to solubilize the lanthanoid-containing compound in a solvent or store it stably for a long period of time, the lanthanoid-containing compound is mixed with a Lewis base, or the lanthanoid-containing compound is reacted with a Lewis base to form a reaction. It is also preferable to use it as an object. The amount of the Lewis base is preferably 0 to 30 mol, more preferably 1 to 10 mol, per 1 mol of the lanthanide. Specific examples of Lewis bases include acetylacetone, tetrahydrofuran, pyridine, N,N-dimethylformamide, thiophene, diphenyl ether, triethylamine, organic phosphorus compounds, monohydric or dihydric alcohols, and the like. The component (a) described so far may be used alone or in combination of two or more.

The component (b) is an aluminoxane and an organoaluminum compound represented by the general formula (1): AlR ^a R ^b R ^c (wherein R ^a and R ^b are the same or differently, represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, and R ^c is the same or different from R ^a and R ^b and represents a hydrocarbon group having 1 to 10 carbon atoms. at least one compound selected from

The aluminoxane (hereinafter also referred to as "alumoxane") is a compound whose structure is represented by the following general formula (4) or (5). Fine Chemicals, 23, (9), 5 (1994), J. Am. Am. Chem. Soc. , 115, 4971 (1993); Am. Chem. Soc. , 117, 6465 (1995).

In general formulas (4) and (5) above, R ⁶ is the same or different and represents a hydrocarbon group having 1 to 20 carbon atoms. p is an integer of 2 or more.

Specific examples of R ⁶ include methyl group, ethyl group, propyl group, butyl group, isobutyl group, t-butyl group, hexyl group, isohexyl group, octyl group and isooctyl group. Among them, a methyl group, an ethyl group, an isobutyl group and a t-butyl group are preferred, and a methyl group is particularly preferred.
Further, p is preferably an integer of 4-100.

Specific examples of the alumoxane include methylalumoxane (hereinafter also referred to as "MAO"), ethylalumoxane, n-propylalumoxane, n-butylalumoxane, isobutylalumoxane, t-butylalumoxane, hexylalumoxane. xane, isohexylalumoxane and the like. Among these, MAO is preferred. The alumoxane can be produced by a known method. For example, a trialkylaluminum or dialkylaluminum monochloride is added to an organic solvent such as benzene, toluene, or xylene, and water, steam, or steam-containing nitrogen is added. It can be produced by adding a gas or a salt having water of crystallization such as copper sulfate pentahydrate or aluminum sulfate 16-hydrate and reacting it. In addition, the said alumoxane may be used individually and may be used in combination of 2 or more types.

Specific examples of the organoaluminum compound represented by the general formula (1) include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-t - butyl aluminum, tripentyl aluminum, trihexyl aluminum, tricyclohexyl aluminum, trioctyl aluminum, diethyl aluminum hydride, di-n-propyl aluminum hydride, di-n-butyl aluminum hydride, diisobutyl aluminum hydride, hydride dihexylaluminum, diisohexylaluminum hydride, dioctylaluminum hydride, diisooctylaluminum hydride, ethylaluminum dihydride, n-propylaluminum dihydride, isobutylaluminum dihydride and the like. Among these, diisobutylaluminum hydride, triethylaluminum, triisobutylaluminum, and diethylaluminum hydride are preferred, and diisobutylaluminum hydride is particularly preferred. The organoaluminum compounds may be used alone or in combination of two or more.

The above component (c) is an iodine-containing compound containing at least one iodine atom in its molecular structure. By using such an iodine-containing compound, BR having a cis content of 94% by mass or more can be easily produced. The iodine-containing compound is not particularly limited as long as it contains at least one iodine atom in its molecular structure. Examples include iodine, trimethylsilyl iodide, diethylaluminum iodide, methyl iodide, butyl iodide, Hexyl iodide, octyl iodide, iodoform, diiodomethane, benzylidene iodide, beryllium iodide, magnesium iodide, calcium iodide, barium iodide, zinc iodide, cadmium iodide, mercury iodide, manganese iodide, iodide Examples include rhenium, copper iodide, silver iodide, and gold iodide.

Among them, the above iodine-containing compounds include general formula (6): R ⁷ _q SiI _4-q (in general formula (6), R ⁷ is the same or different and is a hydrocarbon group having 1 to 20 carbon atoms or represents a hydrogen atom, and q is an integer of 0 to 3.), a silicon iodide compound represented by general formula (7): R ⁸ _r I _4-r (in general formula (7), R ⁸ are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms, and r is an integer of 1 to 3.) or iodine is preferred. Since such silicon iodide compounds, hydrocarbon iodide compounds, and iodine are highly soluble in organic solvents, they are easy to operate and useful for industrial production.

Specific examples of the silicon iodide compound (the compound represented by the general formula (6)) include trimethylsilyl iodide, triethylsilyl iodide, dimethylsilyl diiodide, and the like. Among them, trimethylsilyl iodide is preferred.
Further, specific examples of the iodinated hydrocarbon compound (the compound represented by the general formula (7)) include methyl iodide, butyl iodide, hexyl iodide, octyl iodide, iodoform, diiodomethane, benzylidene iodide, and the like. is mentioned. Among them, methyl iodide, iodoform, and diiodomethane are preferred.

Among these iodine-containing compounds, iodine, trimethylsilyl iodide, triethylsilyl iodide, dimethylsilyl diiodide, methyl iodide, iodoform, and diiodomethane are particularly preferable, and trimethylsilyl iodide is most preferable. The above iodine-containing compounds may be used alone, or two or more of them may be used in combination.

The mixing ratio of each of the above components (components (a) to (c)) may be appropriately set as required. The blending amount of component (a) is, for example, preferably 0.00001 to 1.0 millimoles, more preferably 0.0001 to 0.5 millimoles, per 100 g of the conjugated diene compound.

When the above component (b) is an alumoxane, the amount of the alumoxane to be blended can be represented by the molar ratio between the component (a) and the aluminum (Al) contained in the alumoxane. Aluminum (Al) contained in the alumoxane" (molar ratio) is preferably 1:1 to 1:500, more preferably 1:3 to 1:250, and 1:5 to 1:200. is more preferred.

Further, when the above component (b) is an organoaluminum compound, the amount of the organoaluminum compound to be blended can be represented by the molar ratio of the component (a) to the organoaluminum compound, and "(a) component": The "organoaluminum compound" (molar ratio) is preferably 1:1 to 1:700, more preferably 1:3 to 1:500.

The amount of the component (c) to be blended can be expressed by the molar ratio of the iodine atoms contained in the component (c) to the component (a). (Component (a)) (molar ratio) is preferably 0.5 to 3.0, more preferably 1.0 to 2.5, even more preferably 1.2 to 2.0 preferable.

In addition to the components (a) to (c), the catalyst described above may optionally contain at least one compound selected from the group consisting of conjugated diene compounds and non-conjugated diene compounds, and component (a). The content is preferably 1000 mol or less, more preferably 3 to 1000 mol, and even more preferably 5 to 300 mol, per 1 mol. When the catalyst contains at least one compound selected from the group consisting of conjugated diene compounds and non-conjugated diene compounds, the catalytic activity is further improved, which is preferable. Conjugated diene compounds used at this time include 1,3-butadiene and isoprene. Examples of non-conjugated diene compounds include divinylbenzene, diisopropenylbenzene, triisopropenylbenzene, 1,4-vinylhexadiene, ethylidenenorbornene, and the like.

A catalyst composition containing a mixture of the above components (a) to (c) as a main component is, for example, components (a) to (c) dissolved in a solvent, a conjugated diene compound and a non- It can be prepared by reacting at least one compound selected from the group consisting of conjugated diene compounds. The order of addition of each component in preparation may be arbitrary. However, from the viewpoint of improving the polymerization activity and shortening the polymerization initiation induction period, it is preferable to mix and react the respective components in advance and to let them mature. The aging temperature is preferably 0 to 100°C, more preferably 20 to 80°C. Note that the aging time is not particularly limited. In addition, each component may be brought into contact with each other in the line before being added to the polymerization reactor. The prepared catalyst is stable for several days.

As the BR (I) used in producing the modified BR (I), the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography, that is, the molecular weight distribution (Mw /Mn) is preferably 3.5 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. If the molecular weight distribution exceeds 3.5, the physical properties of the rubber, including breaking properties and low heat build-up, tend to deteriorate. On the other hand, the lower limit of molecular weight distribution is not particularly limited.
The molecular weight distribution (Mw/Mn) means a value calculated from the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight/number average molecular weight). Here, the weight average molecular weight of BR is the polystyrene equivalent weight average molecular weight measured by the GPC method (Gel Permeation Chromatography method). Moreover, the number average molecular weight of BR is the number average molecular weight of polystyrene conversion measured by the GPC method.

The vinyl content and cis content of BR(I) can be easily adjusted by controlling the polymerization temperature. Also, the Mw/Mn can be easily adjusted by controlling the molar ratio of the components (a) to (c).

The Mooney viscosity at 100° C. of BR(I) (ML ₁₊₄ , 100° C.) is preferably in the range of 5-50, more preferably 10-40. This Mooney viscosity can be easily adjusted by controlling the molar ratio of the components (a) to (c).

The 1,2-vinyl bond content (1,2-vinyl bond content, vinyl content) of BR(I) is preferably 0.5% by mass or less, and preferably 0.4% by mass or less. More preferably, it is 0.3% by mass or less. The 1,2-vinyl bond content of BR(I) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more.
The 1,2-vinyl bond content of BR is a value calculated from the signal intensity measured by NMR analysis.

The alkoxysilane compound (hereinafter also referred to as "modifying agent") used in the modification step (A) has two or more reactive groups containing an alkoxysilyl group. The reactive group other than the alkoxysilyl group is not particularly limited in type, but for example, (f): epoxy group, (g): isocyanate group, (h): carbonyl group, and (i): cyano group At least one functional group selected from the group is preferred. The alkoxysilane compound may be a partial condensate, or a mixture of the alkoxysilane compound and the partial condensate.

Here, the term "partial condensate" refers to a product in which a part (that is, not all) of SiOR (OR represents an alkoxy group) of an alkoxysilane compound is SiOSi-bonded by condensation. It is preferable that at least 10% of the polymer chains of the BR used in the modification reaction have living properties.

Specific examples of the alkoxysilane compound include (f); alkoxysilane compound containing an epoxy group (hereinafter also referred to as "epoxy group-containing alkoxysilane compound"), 2-glycidoxyethyltrimethoxysilane, 2 -glycidoxyethyltriethoxysilane, (2-glycidoxyethyl)methyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl)methyl dimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane Among these, 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are more preferred.

Further, (g); an alkoxysilane compound containing an isocyanate group (hereinafter also referred to as an "alkoxysilane compound containing an isocyanate group") includes, for example, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, 3-isocyanatopropyltriisopropoxysilane and the like can be mentioned, among which 3-isocyanatopropyltrimethoxysilane is particularly preferred.

Further, (h); the alkoxysilane compound containing a carbonyl group (hereinafter also referred to as "carbonyl group-containing alkoxysilane compound") includes 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxy Examples include silane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriisopropoxysilane, etc. Among them, 3-methacryloyloxypropyltrimethoxysilane is particularly preferred.

Furthermore, (i); the alkoxysilane compound containing a cyano group (hereinafter also referred to as "cyano group-containing alkoxysilane compound") includes 3-cyanopropyltriethoxysilane, 3-cyanopropyltrimethoxysilane, 3- Cyanopropylmethyldiethoxysilane, 3-cyanopropyltriisopropoxysilane and the like can be mentioned, and among them, 3-cyanopropyltrimethoxysilane is particularly preferred.

Among these modifiers, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-methacryloyloxypropyl Particularly preferred are trimethoxysilane, 3-cyanopropyltrimethoxysilane, and most preferred is 3-glycidoxypropyltrimethoxysilane.
These modifiers may be used alone or in combination of two or more. A partial condensate of the alkoxysilane compound described above can also be used.

In the modification reaction of the modification step (A), the amount of the alkoxysilane compound used is preferably 0.01 to 200 mol, more preferably 0.1 to 150 mol, per 1 mol of the component (a). It is more preferable to have The method of adding the modifier is not particularly limited, but includes a method of collective addition, a method of divided addition, a method of continuous addition, etc. Among them, a method of collective addition is preferable. .

The modification reaction is preferably carried out in a solution, and as this solution, the solution containing the unreacted monomer used in the polymerization can be used as it is. Further, the modification reaction is not particularly limited, and may be carried out using a batch type reactor, or may be carried out continuously using an apparatus such as a multi-stage continuous reactor or an in-line mixer. Moreover, this modification reaction is preferably carried out after completion of the polymerization reaction and before various operations such as solvent removal treatment, water treatment, heat treatment, and polymer isolation.

The temperature for the modification reaction can be the same as the polymerization temperature for polymerizing BR. Specifically, the temperature is preferably 20 to 100°C, more preferably 30 to 90°C. Further, the reaction time in the modification reaction is preferably 5 minutes to 5 hours, more preferably 15 minutes to 1 hour. In the condensation step (B), after introducing the alkoxysilane compound residue to the active terminal of the polymer, if desired, a known anti-aging agent or reaction terminator may be added.

In the modification step (A), in addition to the modifier, in the condensation step (B), a modifier that is condensed with the alkoxysilane compound residue introduced to the active terminal and consumed is further added. preferably. Specifically, it is preferable to add a functional group-introducing agent.

The functional group-introducing agent is not particularly limited as long as it does not substantially cause a direct reaction with the active terminal and remains as an unreacted product in the reaction system. A different alkoxysilane compound, that is, an alkoxysilane compound containing at least one functional group selected from the group consisting of (j); an amino group, (k); an imino group, and (l); a mercapto group. is preferred. The alkoxysilane compound used as the functional group-introducing agent may be a partial condensate, or a mixture of a non-partial condensate of the alkoxysilane compound used as the functional group-introducing agent and the partial condensate. may

Specific examples of the functional group-introducing agent include (j); an alkoxysilane compound containing an amino group (hereinafter also referred to as an "amino group-containing alkoxysilane compound"), 3-dimethylaminopropyl(triethoxy)silane, 3-dimethylaminopropyl(trimethoxy)silane, 3-diethylaminopropyl(triethoxy)silane, 3-diethylaminopropyl(trimethoxy)silane, 2-dimethylaminoethyl(triethoxy)silane, 2-dimethylaminoethyl(trimethoxy)silane, 3- dimethylaminopropyl(diethoxy)methylsilane, 3-dibutylaminopropyl(triethoxy)silane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, aminophenyltrimethoxysilane, aminophenyltriethoxysilane, 3-(N -methylamino)propyltrimethoxysilane, 3-(N-methylamino)propyltriethoxysilane, 3-(1-pyrrolidinyl)propyl(triethoxy)silane, 3-(1-pyrrolidinyl)propyl(trimethoxy)silane, N -(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene- 3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)- 3-(triethoxysilyl)-1-propanamine, N-(cyclohexylidene)-3-(triethoxysilyl)-1-propanamine, and trimethoxysilyl compounds corresponding to these triethoxysilyl compounds, methyldiethoxysilyl compound, ethyldiethoxysilyl compound, methyldimethoxysilyl compound or ethyldimethoxysilyl compound, among others, 3-diethylaminopropyl(triethoxy)silane, 3-dimethylaminopropyl(triethoxy)silane, -aminopropyltriethoxysilane, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)- 1-Propanamine is particularly preferred.

Further, (k); an alkoxysilane compound containing an imino group (hereinafter also referred to as an "imino group-containing alkoxysilane compound"), 3-(1-hexamethyleneimino)propyl(triethoxy)silane, 3-(1 -hexamethyleneimino)propyl(trimethoxy)silane, (1-hexamethyleneimino)methyl(trimethoxy)silane, (1-hexamethyleneimino)methyl(triethoxy)silane, 2-(1-hexamethyleneimino)ethyl(triethoxy) Silane, 2-(1-hexamethyleneimino)ethyl(trimethoxy)silane, 3-(1-heptamethyleneimino)propyl(triethoxy)silane, 3-(1-dodecamethyleneimino)propyl(triethoxy)silane, 3-( 1-hexamethyleneimino)propyl(diethoxy)methylsilane, 3-(1-hexamethyleneimino)propyl(diethoxy)ethylsilane, also 1-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole, 1 -[3-(trimethoxysilyl)propyl]-4,5-dihydroimidazole, 3-[10-(triethoxysilyl)decyl]-4-oxazoline, N-(3-isopropoxysilylpropyl)-4,5 -dihydroimidazole, N-(3-methyldiethoxysilylpropyl)-4,5-dihydroimidazole, among which 3-(1-hexamethyleneimino)propyl(triethoxy)silane, 3-(1-hexamethyleneimino)propyl(trimethoxy)silane, (1-hexamethyleneimino)methyl(trimethoxy)silane, 1-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole, 1- [3-(Trimethoxysilyl)propyl]-4,5-dihydroimidazole is more preferred.

In addition, (l); alkoxysilane compounds containing a mercapto group (hereinafter also referred to as "mercapto group-containing alkoxysilane compounds") include 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 2-mercapto ethyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyl(diethoxy)methylsilane, 3-mercaptopropyl(monoethoxy)dimethylsilane, mercaptophenyltrimethoxysilane, mercaptophenyltriethoxysilane, etc.; Among them, 3-mercaptopropyltriethoxysilane is particularly preferred.

Examples of the functional group-introducing agent include, among these, 3-diethylaminopropyl(triethoxy)silane, 3-dimethylaminopropyl(triethoxy)silane, 3-aminopropyltriethoxysilane, 3-(1-hexamethyleneimino)propyl (Triethoxy)silane, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1- Propaneamine, 3-(1-hexamethyleneimino)propyl(trimethoxy)silane, (1-hexamethyleneimino)methyl(trimethoxy)silane, 1-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole , 1-[3-(trimethoxysilyl)propyl]-4,5-dihydroimidazole, 3-mercaptopropyltriethoxysilane are particularly preferred, and 3-aminopropyltriethoxysilane is most preferred.
These functional group-introducing agents may be used alone or in combination of two or more.

When an alkoxysilane compound is used as the functional group-introducing agent, the amount used is preferably 0.01 to 200 mol, more preferably 0.1 to 150 mol, per 1 mol of component (a).

The functional group-introducing agent is added after the alkoxysilane compound residue is introduced to the active terminal of BR (I) in the modification step (A), and the condensation reaction in the condensation step (B) is completed. Preferably before it starts. When added after the initiation of the condensation reaction, the functional group-introducing agent may not be uniformly dispersed, resulting in a decrease in catalytic performance. Specifically, the addition timing of the functional group-introducing agent is preferably 5 minutes to 5 hours after the initiation of the modification reaction, more preferably 15 minutes to 1 hour after the initiation of the modification reaction.

When the alkoxysilane compound having the functional group is used as the functional group-introducing agent, BR (I) having an active terminal and a substantially stoichiometric amount of modifier added to the reaction system are modified. A reaction is caused to introduce alkoxysilyl groups to substantially all of the active terminals, and by adding the functional group-introducing agent, more alkoxysilane compound residues than the equivalent amount of the active terminals of this BR are introduced. It will be.

From the viewpoint of reaction efficiency, the condensation reaction between alkoxysilyl groups preferably occurs between a free alkoxysilane compound and an alkoxysilyl group at the end of BR, and in some cases between the alkoxysilyl groups at the end of BR. Reaction between free alkoxysilane compounds is not preferred. Therefore, when an alkoxysilane compound is newly added as a functional group-introducing agent, the hydrolyzability of the alkoxysilyl group is preferably lower than the hydrolyzability of the alkoxysilyl group introduced at the BR terminal.

For example, a compound containing a highly hydrolyzable trimethoxysilyl group is used as the alkoxysilane compound used for the reaction with the active terminal of BR(I), and the alkoxysilane compound newly added as the functional group introducing agent is and a compound containing an alkoxysilyl group (for example, a triethoxysilyl group) having lower hydrolyzability than the trimethoxysilyl group-containing compound is preferred.

The condensation step (B) is carried out in the presence of a condensation catalyst containing at least one element selected from the group consisting of elements included in Groups 4, 12, 13, 14 and 15 of the periodic table. The second step is the condensation reaction of the residue of the alkoxysilane compound introduced to the active terminal.

The condensation catalyst is particularly limited as long as it contains at least one element selected from the group consisting of elements included in Groups 4, 12, 13, 14 and 15 of the periodic table. but for example titanium (Ti) (group 4), tin (Sn) (group 14), zirconium (Zr) (group 4), bismuth (Bi) (group 15) and aluminum (Al) ( Group 13) preferably contains at least one element selected from the group consisting of.

Specific examples of the condensation catalyst include condensation catalysts containing tin (Sn), such as bis(n-octanoate)tin, bis(2-ethylhexanoate)tin, bis(laurate)tin, bis(naphthoenate), ) tin, bis(stearate)tin, bis(oleate)tin, dibutyltin diacetate, dibutyltin di-n-octanoate, dibutyltin di-2-ethylhexanoate, dibutyltin dilaurate, dibutyltin malate, dibutyltin bis(benzyl malate), Dibutyltin bis(2-ethylhexylmalate), di-n-octyltin diacetate, di-n-octyltin di-n-octanoate, di-n-octyltin di-2-ethylhexanoate, di-n-octyltin dilaurate, di-n-octyltin di-n-octyltinbis(benzyl malate), di-n-octyltinbis(2-ethylhexylmalate) and the like.

Examples of condensation catalysts containing zirconium (Zr) include tetraethoxyzirconium, tetra-n-propoxyzirconium, tetra-i-propoxyzirconium, tetra-n-butoxyzirconium, tetra-sec-butoxyzirconium, tetra-tert-butoxyzirconium, tetra(2- ethylhexyl oxide) zirconium, zirconium tributoxy sterate, zirconium tributoxy acetylacetonate, zirconium dibutoxy bis (acetylacetonate), zirconium tributoxyethyl acetoacetate, zirconium butoxy acetylacetonate bis (ethyl acetoacetate), zirconium tetrakis ( acetylacetonate), zirconium diacetylacetonate bis(ethylacetoacetate), bis(2-ethylhexanoate)zirconium oxide, bis(laurate)zirconium oxide, bis(naphtate)zirconium oxide, bis(stearate)zirconium oxide, bis(oleate)zirconium oxide, bis(linoleate)zirconium oxide, tetrakis(2-ethylhexanoate)zirconium, tetrakis(laurate)zirconium, tetrakis(naphtate)zirconium, tetrakis(stearate)zirconium, tetrakis(oleate)zirconium, Tetrakis(linoleate) zirconium and the like can be mentioned.

Examples of condensation catalysts containing bismuth (Bi) include tris (2-ethylhexanoate) bismuth, tris (laurate) bismuth, tris (naphtate) bismuth, tris (stearate) bismuth, tris (oleate) bismuth, tris ( linoleate) and bismuth.

Condensation catalysts containing aluminum (Al) include, for example, triethoxyaluminum, tri-n-propoxyaluminum, tri-i-propoxyaluminum, tri-n-butoxyaluminum, trisec-butoxyaluminum, tri-tert-butoxyaluminum, tri(2- ethylhexyl oxide) aluminum, aluminum dibutoxystearate, aluminum dibutoxyacetylacetonate, aluminum butoxybis(acetylacetonate), aluminum dibutoxyethylacetoacetate, aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetate), tris(2-ethylhexanoate)aluminum, tris(laurate)aluminum, tris(naphtate)aluminum, tris(stearate)aluminum, tris(oleate)aluminum, tris(linoleate)aluminum and the like.

Examples of condensation catalysts containing titanium (Ti) include tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetra-i-propoxytitanium, tetra-n-butoxytitanium, tetra-n-butoxytitanium oligomer, and tetrasec-butoxytitanium. , tetra-tert-butoxy titanium, tetra(2-ethylhexyloxide) titanium, bis(octanediolate)bis(2-ethylhexyloxide)titanium, tetra(octanediolate)titanium, titanium lactate, titanium dipropoxybis(triethanolamine) titanium dibutoxybis(triethanolamine), titanium tributoxystearate, titanium tripropoxystearate, titanium tripropoxyacetylacetonate, titanium dipropoxybis(acetylacetonate), titanium tripropoxyethylacetoacetate, Titanium propoxyacetylacetonate bis(ethylacetoacetate), Titanium tributoxyacetylacetonate, Titanium dibutoxy bis(acetylacetonate), Titanium tributoxyethylacetoacetate, Titanium butoxyacetylacetonate bis(ethylacetoacetate), Titanium tetrakis (acetylacetonate), titanium diacetylacetonate bis(ethylacetoacetate), bis(2-ethylhexanoate) titanium oxide, bis(laurate) titanium oxide, bis(naphtate) titanium oxide, bis(stearate) titanium oxide , bis(oleate) titanium oxide, bis(linoleate) titanium oxide, tetrakis(2-ethylhexanoate) titanium, tetrakis(laurate) titanium, tetrakis(naphtate) titanium, tetrakis(stearate) titanium, tetrakis(oleate) titanium , tetrakis(linoleate) titanium, and the like.

Among these, a condensation catalyst containing titanium (Ti) is more preferable as the condensation catalyst. Among the condensation catalysts containing titanium (Ti), alkoxides, carboxylates or acetylacetonate complexes of titanium (Ti) are more preferred. Tetra i-propoxytitanium (tetraisopropyltitanate) is particularly preferred. By using a condensation catalyst containing titanium (Ti), the condensation reaction of the residue of the alkoxysilane compound used as a modifier and the residue of the alkoxysilane compound used as a functional group introducing agent is more effectively promoted. can be done.

The amount of the condensation catalyst used is such that the number of moles of the various compounds that can be used as the condensation catalyst is 0.1 to 10 moles per 1 mole of the total amount of alkoxysilyl groups present in the reaction system. is preferred, and 0.3 to 5 mol is particularly preferred.

The condensation catalyst can be added before the modification reaction, but is preferably added after the modification reaction and before starting the condensation reaction. Specifically, the timing of addition of the condensation catalyst is preferably 5 minutes to 5 hours after the initiation of the modification reaction, more preferably 15 minutes to 1 hour after the initiation of the modification reaction.

The condensation reaction in the condensation step (B) is preferably carried out in an aqueous solution, and the temperature during the condensation reaction is preferably 85 to 180°C, more preferably 100 to 170°C, and 110 to 150°C. is particularly preferred.

The pH of the aqueous solution in which the condensation reaction is performed is preferably 9-14, more preferably 10-12. By setting the pH of the aqueous solution within this range, the condensation reaction is promoted, and the stability of the modified BR(I) over time can be improved.

The reaction time of the condensation reaction is preferably 5 minutes to 10 hours, more preferably about 15 minutes to 5 hours. Also, the pressure in the reaction system during the condensation reaction is preferably 0.01 to 20 MPa, more preferably 0.05 to 10 MPa.

The form of the condensation reaction is not particularly limited, and may be carried out using a batch type reactor, or may be carried out continuously using an apparatus such as a multi-stage continuous reactor. Moreover, you may remove a solvent simultaneously with this condensation reaction.

After carrying out the condensation reaction as described above, conventionally known post-treatments can be carried out to obtain the desired modified BR.

As another example of the modified BR, (3) tin-modified BR can be used.
The tin-modified BR is not particularly limited, but a tin-modified butadiene rubber (BR) that is polymerized with a lithium initiator, has a tin atom content of 50 to 3000 ppm, a vinyl content of 5 to 50% by mass, and a molecular weight distribution of 2 or less. preferable.

The tin-modified BR is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and the ends of the tin-modified BR molecules are bound by tin-carbon bonds. is preferred.

Examples of the lithium initiator include lithium-based compounds such as alkyllithium and aryllithium.
Further, examples of the tin compound include tin tetrachloride and butyltin trichloride.

The tin atom content of the tin-modified BR is preferably 50 ppm or more. Also, it is preferably 3000 ppm or less, more preferably 300 ppm or less.

The tin-modified BR preferably has a molecular weight distribution (Mw/Mn) of 2 or less. Although the lower limit of the molecular weight distribution is not particularly limited, it is preferably 1 or more. The tin-modified BR preferably has a vinyl content of 5% by mass or more. Moreover, 50 mass % or less is preferable and 20 mass % or less is more preferable.

In the rubber composition, the total content of isoprene-based rubber and BR in 100% by mass of the rubber component is 60% by mass or more, preferably 80% by mass or more, from the viewpoint of performance balance between ice and snow performance and abrasion resistance. , more preferably 90% by mass or more, and may be 100% by mass.

The rubber composition may contain other rubber components as long as the above effects are not impaired. Other rubber components include diene rubbers such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). be done.

(silica)
The rubber composition contains silica as a filler from the viewpoint of performance balance between performance on ice and snow and abrasion resistance. Examples of silica include dry silica (anhydrous silica) and wet silica (hydrous silica). Among them, wet-process silica is preferable because it has many silanol groups. Commercially available products of Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used. These may be used alone or in combination of two or more.

The content of silica is 1 part by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is 500 parts by mass or less, preferably 300 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. When the amount is within the above range, good dispersibility of silica is obtained, and there is a tendency to obtain an excellent balance of performance on ice and snow, abrasion resistance, and the like.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 70 m ² /g or more, more preferably 160 m ² /g or more, still more preferably 190 m ² /g or more. The upper limit of N ₂ SA of silica is not particularly limited, but is preferably 500 m ² /g or less, more preferably 300 m ² /g or less, and still more preferably 250 m ² /g or less. When the amount is within the above range, good dispersibility of silica is obtained, and there is a tendency to obtain an excellent balance of performance on ice and snow, abrasion resistance, and the like.
The N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

In the rubber composition, the silica content in the total content of 100% by mass of silica and carbon black is preferably 50% by mass or more, and 80% by mass or more, from the viewpoint of performance balance between performance on ice and snow and abrasion resistance. is more preferable, and 90% by mass or more is even more preferable.

(Silane coupling agent)
When the rubber composition contains silica, it preferably further contains a silane coupling agent.
The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) ) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3- sulfides such as triethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; Vinyl compounds such as triethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltriethoxysilane; glycidoxy-based such as methoxysilane; nitro-based such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. be done. As commercially available products, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, relative to 100 parts by mass of silica. The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, effects commensurate with the blending amount are obtained, and there is a tendency to obtain a good balance between performance on ice and snow and wear resistance.

(Carbon black)
The rubber composition preferably contains carbon black as a filler from the viewpoint of the performance balance between antistatic properties and abrasion resistance. Examples of carbon black include, but are not limited to, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin Nikka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. can. These may be used alone or in combination of two or more.

The content of carbon black is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. The above content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 7 parts by mass or less. When the amount is within the above range, good dispersibility of carbon black can be obtained, and there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and fuel efficiency.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 50 m ² /g or more, more preferably 80 m ² /g or more, and even more preferably 100 m ² /g or more. The N ₂ SA is preferably 200 m ² /g or less, more preferably 150 m ² /g or less, and even more preferably 130 m ² /g or less. When the amount is within the above range, good dispersibility of carbon black is obtained, and there is a tendency to obtain a good balance between performance on ice and snow and wear resistance.
The nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

(Terpene resin)
The rubber composition is a terpene resin having a predetermined softening point, α-pinene unit content, β-pinene unit content and limonene unit content from the viewpoint of performance balance on ice and snow and abrasion resistance. include.

The content of the terpene-based resin is 0.1 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. The above content is 100 parts by mass or less, preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like.

The terpene-based resin has a softening point of 60 to 150°C. The lower limit is preferably 70°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. The upper limit is preferably 140°C or lower, more preferably 135°C or lower. When the content is above the lower limit, good wear resistance tends to be obtained, and when the content is below the lower limit, good workability tends to be obtained.
The softening point is a value measured according to ASTM D6090 (published in 1997).

The terpene resin preferably has a number average molecular weight (Mn) of 500-775. The lower limit is more preferably 580 or higher, even more preferably 620 or higher. The upper limit is more preferably 765 or less, even more preferably 755 or less. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like.

The terpene-based resin preferably has a z-average molecular weight (Mz) of 1,300 to 1,600. The lower limit is more preferably 1310 or higher, and even more preferably 1320 or higher. The upper limit is more preferably 1570 or less, even more preferably 1550 or less. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like.

The terpene resin preferably has a weight average molecular weight (Mw) of 800-1100. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like.

The terpene resin preferably has a molecular weight distribution (Mw/Mn) of 1.30 to 1.70. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like.

Mn, Mw, and Mz are values measured using gel permeation/size exclusion chromatography (GPC-SEC) described in ASTM D5296 (published in 2005).

The terpene resin preferably has a glass transition temperature (Tg) of 25 to 90°C. The lower limit is more preferably 35°C or higher, and even more preferably 38°C or higher. The upper limit is more preferably 85°C or lower, and even more preferably 81°C or lower. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like.
Note that Tg is a value measured according to ASTM D 6604 (published in 2013) using a differential scanning calorimeter SC Q2000 from TA Instruments.

The terpene-based resin has a limonene unit content (content of limonene units in 100% by mass of the terpene-based resin) of 10% by mass or less. It is preferably 5% by mass or less, more preferably 1% by mass or less, and still more preferably 0% by mass.

The terpene-based resin includes a homopolymer obtained by polymerizing one type of terpene (terpene monomer), a copolymer obtained by copolymerizing two or more types of terpenes, and one or more types of terpenes and one or more types other than terpenes. Any of copolymers with the monomers may be used.

The basic molecular formula of the terpene constituting the terpene-based resin is (C ₅ H ₈ ) _n (n is the number of linked isoprene units (n is 2 or more)). Examples of suitable terpenes include α-pinene, β-pinene, δ-3-carene, β-phellandrene; decomposition products; combinations thereof; and the like. Among them, α-pinene and β-pinene are preferred, and α-pinene is more preferred.

The terpene-based resin preferably has a terpene unit content (the content of terpene units in 100% by mass of the terpene-based resin) of 80% by mass or more from the viewpoint of performance balance between performance on ice and snow and abrasion resistance. . More preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 99% by mass or more. In this case, the terpene-based resin may be either a homopolymer or a copolymer having only terpene as a structural unit.

As the terpene-based resin, a polymer having α-pinene units and a polymer having α-pinene units and β-pinene units can be preferably used. Specific examples include α-pinene homopolymers and copolymers having α-pinene units and β-pinene units.

In the terpene-based resin, the α-pinene unit content (the content of α-pinene units in 100% by mass of the terpene-based resin) is 65 to 100 mass from the viewpoint of performance balance between performance on ice and snow and abrasion resistance. %. It is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and may be 100% by mass.

In the terpene-based resin, the β-pinene unit content (the content of β-pinene units in 100% by mass of the terpene-based resin) is 0 to 35% by mass from the viewpoint of the balance of performance on ice and snow and abrasion resistance. is within the range of The content is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, particularly preferably 10% by mass or less, and may be 0% by mass.

In the terpene-based resin, the total content of α-pinene units and β-pinene units (total content of α-pinene units and β-pinene units in 100% by mass of terpene-based resin) is the performance on ice and snow and abrasion resistance It is preferably 80% by mass or more from the viewpoint of the balance of properties and performance. More preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 99% by mass or more.

The terpene-based resin can be synthesized, for example, by cationic polymerization of one or more terpene monomers using a Lewis acid catalyst.
The Lewis acid catalyst is not particularly limited, and includes BF ₃ , BBr ₃ , AlF ₃ , AlBr ₃ , TiCl ₄ , TiBr ₄ , TiL ₄ , FeCl ₃ , FeCl ₂ , SnCl ₄ , WCl ₆ , MoCl ₅ , ZrCl ₄ , SbCl _{metal halides} such as _{3 , SbCl 5 , TeCl 2 and ZnCl 2 ;} ( _{i -} Bu) metal alkyl compounds such as _{AlCl 2} , Me ₄ Sn, Et ₄ Sn, Bu ₄ Sn and Bu _{3 SnCl} ; represents an alkyl group or an aryl group, x represents an integer of 1 or 2, and y represents an integer of 1 to 3.) and the like. Also, (i) combinations of AlCl ₃ and alkyl tertiary amines such as trimethylamine; (ii) AlCl ₃ and organosilicon compounds such as trialkylsilicon halides, lower dialkylphenylsilicon halides, hexaalkyldisiloxanes; (iii) a combination of AlCl ₃ and an organic germanium halide such as trimethylgermanium chloride or triethylgermanium ethoxide; (iv) a lower alkyl group having 1 to 18 carbon atoms;

When cationic polymerization is carried out by solution polymerization, the solvent that can be used is not particularly limited as long as the terpene monomer can be polymerized, and examples thereof include halogenated hydrocarbons, aromatic hydrocarbons, aliphatic hydrocarbons, and the like. Available. Specifically, halogenated hydrocarbon solvents (methylene chloride, chloroform, 1,1-dichloromethane, 1,2-dichloroethane, n-propyl chloride, 1-chloro-n-butane, 2-chloro-n-butane, etc. ); aromatic hydrocarbon solvents (benzene, toluene, xylene, anisole, naphtha, etc.); aliphatic hydrocarbon solvents (pentane, hexane, heptane, octane, cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, etc.) be done. The polymerization reaction can be carried out in a temperature range of, for example, -120 to 100°C, -80 to 80°C, 5 to 50°C.

(liquid plasticizer)
The rubber composition preferably contains a liquid plasticizer from the viewpoint of workability, performance on ice and snow, wear resistance performance balance, and the like. A liquid plasticizer is a plasticizer that is in a liquid state at room temperature (25° C.).

The content of the liquid plasticizer is preferably 0.1 parts by mass or more, more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. The above content is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like. In addition, it is preferable that the content of the polar plasticizer (liquid), which will be described later, is the same.

The liquid plasticizer preferably has a glass transition temperature (Tg) of -60°C or lower. It is more preferably -80°C or lower, still more preferably -90°C or lower. Although the lower limit is not particularly limited, it is preferably -200°C or higher, more preferably -150°C or higher. By setting the content within the above range, there is a tendency to obtain a good balance of performance on ice and snow, wear resistance, and the like. In addition, it is preferable that the Tg of the polar plasticizer (liquid) described later is also the same.
In addition, Tg can be measured by the method similar to the above-mentioned terpene-type resin.

Liquid plasticizers include oils, liquid diene-based polymers, polar plasticizers (ester-based plasticizers, etc.), and the like. Among them, polar plasticizers such as ester-based plasticizers (fatty acid ester-based plasticizers, phosphate-based plasticizers (phosphate-based plasticizers), etc.) are preferable from the viewpoint of performance balance between performance on ice and snow and wear resistance. These may be used alone or in combination of two or more.

Oils include, for example, process oils, vegetable oils, or mixtures thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, and olive oil. , sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Commercially available products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., Fuji Kosan Co., Ltd., Products such as Nisshin OilliO Group Co., Ltd. can be used.

Examples of the liquid diene polymer include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene butadiene styrene block copolymer (liquid SBS block polymer), liquid styrene isoprene styrene block copolymer (liquid SIS block polymer), liquid farnesene polymer, liquid farnesene butadiene copolymer, and the like. . These may be modified with a polar group at the terminal or main chain.

Examples of ester-based plasticizers include the aforementioned vegetable oils; synthetic products such as glycerin fatty acid monoesters, glycerin fatty acid diesters and glycerin fatty acid triesters; processed products of vegetable oils; and phosphate esters (phosphates, mixtures thereof, etc.).

（式中、Ｒ^１１は、炭素数１～８の直鎖若しくは分枝状アルキル基、炭素数１～８の直鎖若しくは分枝状アルケニル基、又は１～５個のヒドロキシル基で置換された炭素数２～６の直鎖又は分枝状アルキル基を表す。Ｒ^１２は、炭素数１１～２１のアルキル基又はアルケニル基を表す。） As an ester-based plasticizer, for example, a fatty acid ester represented by the following formula can be preferably used.

(wherein R ¹¹ is a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkenyl group having 1 to 8 carbon atoms, or a hydroxyl group substituted with 1 to 5 represents a linear or branched alkyl group having 2 to 6 carbon atoms, and R ¹² represents an alkyl or alkenyl group having 11 to 21 carbon atoms.)

Examples of R ¹¹ include a methyl group, an ethyl group, a 2-ethylhexyl group, an isopropyl group, an octyl group, groups in which these groups are substituted with 1 to 5 hydroxyl groups, and the like. Examples of R ¹² include linear or branched alkyl groups and alkenyl groups such as lauryl group, myristyl group, palmityl group, stearyl group and oleyl group.

Examples of fatty acid esters include alkyl oleate, alkyl stearate, alkyl linoleate, and alkyl palmitate. Among them, alkyl oleate (methyl oleate, ethyl oleate, 2-ethylhexyl oleate, isopropyl oleate, octyl oleate, etc.) is preferable. In this case, the content of alkyl oleate in 100% by mass of the fatty acid ester is preferably 80% by mass or more.

Fatty acid esters include fatty acids (oleic acid, stearic acid, linoleic acid, palmitic acid, etc.) and alcohols (ethylene glycol, glycerol, trimethylolpropane, pentaerythritol, erythritol, xylitol, sorbitol, dulcitol, mannitol, inositol, etc.). Also included are fatty acid monoesters and fatty acid diesters of Among them, oleic acid monoester is preferable. In this case, the content of oleic acid monoester in 100% by mass of the total amount of fatty acid monoester and fatty acid diester is preferably 80% by mass or more.

Phosphate esters can also be suitably used as ester plasticizers.
The phosphate ester is preferably a compound having 12 to 30 carbon atoms, and trialkyl phosphate having 12 to 30 carbon atoms is particularly preferable. The number of carbon atoms in the trialkyl phosphate means the total number of carbon atoms in the three alkyl groups, and the three alkyl groups may be the same group or different groups. Alkyl groups include, for example, linear or branched alkyl groups, which may contain heteroatoms such as oxygen atoms, or may be substituted with halogen atoms such as fluorine, chlorine, bromine, and iodine.

The phosphate ester includes a mono-, di-, or triester of phosphoric acid with a monoalcohol having 1 to 12 carbon atoms or a (poly)oxyalkylene adduct thereof; Compounds substituted with a phenyl group; and other known phosphate ester plasticizers. Specifically, tris(2-ethylhexyl) phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate , tris(2-butoxyethyl) phosphate and the like.

(other materials)
The rubber composition may contain a solid resin other than the terpene-based resin (a resin that is solid at room temperature (25° C.)). Examples of solid resins include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenol resins, rosin resins, petroleum resins, acrylic resins, and the like. When other solid resin is included, the total content of the terpene-based resin and the solid resin other than the terpene-based resin (other resin) is preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the rubber component. , 10 to 70 parts by mass is more preferable.

From the viewpoint of crack resistance, ozone resistance, etc., the rubber composition preferably contains an anti-aging agent.

Antiaging agents are not particularly limited, but naphthylamine antiaging agents such as phenyl-α-naphthylamine; diphenylamine antiaging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine. ; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylene p-phenylenediamine antioxidants such as diamines; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methyl monophenol antioxidants such as phenol and styrenated phenol; bis, tris and polyphenols such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane anti-aging agent, etc. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 , 2-dihydroquinoline polymers are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis, etc. can be used.

The content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the rubber component. By making it more than the lower limit, there is a tendency that sufficient ozone resistance can be obtained. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less. By making it below the upper limit, there is a tendency that a good tire appearance can be obtained.

The rubber composition preferably contains stearic acid. The stearic acid content is preferably 0.5 to 10 parts by mass or more, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

As the stearic acid, conventionally known ones can be used, for example, NOF Corporation, NOF, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acids Co., Ltd. products can be used. .

The rubber composition preferably contains zinc oxide. The content of zinc oxide is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

As the zinc oxide, conventionally known ones can be used. products can be used.

Wax may be blended in the rubber composition. The wax is not particularly limited, and examples thereof include petroleum waxes and natural waxes. Synthetic waxes obtained by refining or chemically treating a plurality of waxes can also be used. These waxes may be used alone or in combination of two or more.

Examples of petroleum wax include paraffin wax and microcrystalline wax. The natural wax is not particularly limited as long as it is derived from a resource other than petroleum. Examples include plant waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; beeswax, lanolin, spermaceti, and the like. animal waxes; mineral waxes such as ozokerite, ceresin and petrolactam; and refined products thereof. As commercially available products, for example, products of Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used. The wax content may be appropriately set from the viewpoint of ozone resistance and cost.

It is preferable to add sulfur to the rubber composition from the viewpoint of forming appropriate crosslinked chains in the polymer chains and imparting good performance.

The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and still more preferably 0.7 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. Good performance tends to be obtained by setting it within the above range.

Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur and the like commonly used in the rubber industry. As commercially available products, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Io Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nippon Kantan Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The rubber composition preferably contains a vulcanization accelerator.
The content of the vulcanization accelerator is not particularly limited, and may be freely determined according to the desired vulcanization speed and crosslink density. , preferably 0.5 to 7 parts by mass.

The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), tetrabenzyl thiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among them, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

In addition to the components described above, the rubber composition may optionally contain compounding agents commonly used in the tire industry, such as release agents.

As a method for producing the rubber composition, a known method can be used. For example, the above components can be kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanized. .

As kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30°C. seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100°C or lower, preferably room temperature to 80°C. A composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is generally 120-200°C, preferably 140-180°C.

The rubber composition is produced by a general method. That is, it can be produced by kneading each of the above components with a Banbury mixer, a kneader, an open roll, or the like, and then vulcanizing. The rubber composition can be suitably used as a tire tread, particularly a studless tire tread (single-layer tread, multi-layer tread cap tread).

The rubber composition (vulcanized rubber composition) should have an E* (complex elastic modulus) of 3.0 to 10.0 MPa at 0° C. from the viewpoint of performance balance between ice and snow performance and handling stability. preferable. The lower limit is more preferably 3.5 MPa or more. The upper limit is more preferably 9.0 MPa or less, still more preferably 8.0 MPa or less.

The rubber composition (vulcanized rubber composition) has a difference in E* (complex elastic modulus) at -10 ° C. and 10 ° C. ((at -10 ° C. E*)-(E* at 10° C.)) is preferably 10.0 MPa or less. 8.0 MPa or less is more preferable, and 7.0 MPa or less is even more preferable.

From the viewpoint of performance on ice, the rubber composition (vulcanized rubber composition) preferably has a tan δ (loss tangent) at 0° C. of 0.14 to 0.26. The upper limit is more preferably 0.25 or less.

(pneumatic tire)
The pneumatic tire of the present invention is manufactured by a normal method using the rubber composition. That is, the rubber composition blended with the above components is extruded in the unvulcanized stage according to the shape of the tread (cap tread, etc.), and molded together with other tire components on a tire molding machine by a normal method. to form an unvulcanized tire. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer. The tire of the present invention can be suitably used as a studless tire (especially a studless tire for passenger cars).

EXAMPLES The present invention will be specifically described based on Examples, but the present invention is not limited to these.

Various chemicals used in Examples and Comparative Examples are described below.
NR: RSS#3
BR: BR150B manufactured by Ube Industries (95% by mass or more of cis)
Carbon black: SEAST N220 manufactured by Mitsubishi Chemical Corporation
Silica: ZEOSIL P200MP (N ₂ SA215 m ² /g) manufactured by Rothia
Silane coupling agent: Si-69 manufactured by Evonik Degussa
Terpene resin 1: α-pinene homopolymer (softening point 130 ° C., Mn 742 g / mol, Mz 1538 g / mol, Mw 1055 g / mol, Mw / Mn 1.42, Tg 81 ° C., limonene unit content 0% by mass)
Terpene resin 2: pinene polymer (α-pinene 90% by mass, β-pinene 10% by mass, softening point 130 ° C., Mn 657 g / mol, Mz 1332 g / mol, Mw 917 g / mol, Mw / Mn 1.40, Tg 80 ° C., limonene unit Content rate 0% by mass)
Terpene resin 3: pinene polymer (α-pinene 20% by mass, β-pinene 80% by mass, softening point 130 ° C., Mn 790 g / mol, Mz 1891 g / mol, Mw 1101 g / mol, Mw / Mn 1.57, Tg 78 ° C., limonene unit Content rate 0% by mass))
Resin 4: α-methylstyrene resin (Sylvares SA120 made by Kraton Polymer, softening point 120° C.)
Wax: Ozoace wax manufactured by Nippon Seiro Co., Ltd. Antioxidant: Nocrac 6C manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Liquid plasticizer 1: PS-32 (mineral oil) manufactured by Idemitsu Kosan Co., Ltd.
Liquid plasticizer 2: Glycerin fatty acid monoester (H&R Pioneer TP130B, monoester of high oleic sunflower oil, Tg -110°C)
Liquid plasticizer 3: Tris (2-ethylhexyl) phosphate (phosphine plasticizer, Disflmoll TOF manufactured by LANXESS, Tg -105°C)
Stearic acid: zinc paulownia oxide manufactured by NOF Corporation: zinc oxide manufactured by Mitsui Kinzoku Co., Ltd. Type 2 sulfur: powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Ouchi Shinko Kagaku Kogyo Co., Ltd. ) manufactured Noxcella NS

<Examples and Comparative Examples>
According to the compounding recipe shown in Table 1, using a 1.7 L Banbury mixer, natural rubber and silica, butadiene rubber and silica were added, and each was kneaded at 150°C for 3 minutes to give a kneaded product (masterbatch). Obtained. Next, materials other than sulfur and a vulcanization accelerator were added to the obtained masterbatch, and the mixture was kneaded at 150° C. for 2 minutes to obtain a kneaded product. Further, sulfur and a vulcanization accelerator were added and kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition.
Each unvulcanized rubber composition thus obtained was vulcanized at 170° C. for 15 minutes to obtain a vulcanized rubber composition (test piece).

Further, each of the obtained unvulcanized rubber compositions was molded in the shape of a cap tread, bonded together with other tire members, and vulcanized at 170 ° C. for 15 minutes to obtain a test studless tire (tire size: 195 /65R15) were prepared.

The obtained vulcanized rubber compositions (test pieces) and studless tires for testing were stored at room temperature in a dark place for three months, and then evaluated as follows. Table 1 shows the results.

<Ice Performance>
Using studless tires for testing, actual vehicle performance on ice was evaluated under the following conditions. The test was conducted at the Hokkaido Nayoro test course of Sumitomo Rubber Industries, Ltd., and the temperature was 0 to -5°C. The test tire was mounted on a domestically produced 2000 cc FR vehicle, and the stopping distance on ice required to depress the lock brake at a speed of 30 km/h and stop was measured. Using Comparative Example 1 as a reference, it was calculated from the following formula. A larger index indicates better performance on ice.
(Performance on ice) = (braking stopping distance of Comparative Example 1) / (stopping distance of each formulation) x 100

<Steering stability>
Studless tires for testing were attached to all wheels of an actual vehicle for testing (a domestic FF vehicle, engine displacement: 2000 cc), and meandering driving was performed. At that time, a test driver sensory-evaluated the stability of control during steering, and the result was indexed with Comparative Example 1 being 100. A larger index indicates better steering stability.

<Rolling resistance (fuel efficiency)>
Using a rolling resistance tester, the studless tire for testing was run with a rim (15 × 6 JJ), internal pressure (230 kPa), load (3.43 kN), speed (80 km / h). Rolling resistance was measured, It is indicated by an index when Comparative Example 1 is set to 100. The larger the index, the smaller the rolling resistance and the better the fuel efficiency.

<Abrasion resistance>
The vulcanized rubber composition was tested using a Lambourn abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd. under the conditions of a surface rotation speed of 50 m/min, an additional load of 3.0 kg, a sandfall amount of 15 g/min, and a slip rate of 20%. , the amount of wear was measured, and the reciprocal of the amount of wear was calculated. Taking the reciprocal of the wear amount of Comparative Example 1 as 100, the reciprocal of the wear amount of the other formulations was expressed as an index. A larger index indicates better wear resistance.

From Table 1, a terpene resin having a predetermined softening point, α-pinene unit content, β-pinene unit content, and limonene unit content is added to a compound containing isoprene rubber, butadiene rubber, and silica in a predetermined compound. In the example, the performance balance between performance on ice and snow and wear resistance was remarkably improved. In addition, the balance of performance on ice and snow, wear resistance, steering stability, and fuel economy has been remarkably improved.

Claims (13)

A rubber component containing isoprene rubber and butadiene rubber, silica, a softening point of 60 to 150 ° C., an α-pinene unit content of 65 to 100% by mass, a β-pinene unit content of 0 to 35% by mass, and a limonene unit content Containing 10% by mass or less of a terpene-based resin and a fatty acid ester-based plasticizer ,
The content of the isoprene rubber in 100% by mass of the rubber component is 5 to 80% by mass, the content of the butadiene rubber is 5 to 80% by mass, and the total content of the isoprene rubber and the butadiene rubber is 60% by mass. % or more,
A rubber composition for tires, wherein the silica content is 1 to 500 parts by mass and the terpene resin content is 0.1 to 100 parts by mass with respect to 100 parts by mass of the rubber component. The terpene-based resin is an α-pinene homopolymer, a terpene-based resin having an α-pinene unit content of 99% by mass or more, and a copolymer having an α-pinene unit and a β-pinene unit. The rubber composition for tires according to claim 1, which is at least one of The rubber composition for tires according to claim 1 or 2, wherein the terpene resin has a number average molecular weight of 500-775 and a z-average molecular weight of 1300-1600. The rubber composition for tires according to any one of claims 1 to 3, wherein the content of silica is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition for tires according to any one of claims 1 to 4, wherein the silica has a nitrogen adsorption specific surface area of 160 m ² /g or more. The rubber composition for tires according to any one of claims 1 to 4, wherein the silica has a nitrogen adsorption specific surface area of 190 m ² /g or more. The rubber composition for tires according to any one of claims 1 to 6, wherein the content of carbon black is 0.1 to 50 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition for tires according to any one of claims 1 to 7, wherein the butadiene rubber has a cis content of 90% by mass or more. The rubber composition for tires according to any one of claims 1 to 8, comprising 0.1 to 100 parts by mass of the polar plasticizer with respect to 100 parts by mass of the rubber component. The rubber composition for tires according to claim 9, wherein the polar plasticizer has a glass transition temperature of -80°C or lower. Claims 1 to 10, wherein E* at 0°C is 3.0 to 8.0, the difference between E* at -10°C and 10°C is 10.0 or less, and tan δ at 0°C is 0.14 to 0.26. The rubber composition for tires according to any one of the above. A pneumatic tire having a tread made of the rubber composition according to any one of claims 1 to 11. A studless tire having a tread made of the rubber composition according to any one of claims 1 to 11.